Fluconazole Interactions

Fluconazole inhibits CYP2C9 and CYP3A4, the enzymes that clear warfarin, and can rapidly raise INR by 50 to 100 percent or more within two to three days of starting, with documented cases of major bleeding and death.

Fluconazole is a moderate inhibitor of CYP3A4 and grapefruit juice inhibits intestinal CYP3A4; the inhibition is additive, which can raise plasma levels of any third drug that depends on CYP3A4 for clearance.